oh hon, it must be tough for you! But I agree with what everyone else has said.
He's 21 and this is his gf, could be his lifelong partner, probably worth seeing her as such now?
Now, if she were YOUR daughter, would you be calling her controlling? Or is it just because you feel she's taken your son from you? Imagine being HER parent, if her and your son had decided to come to your party instead of theirs? Would you son be labelled controlling then?
Just another way to look at it, and definitely not meant in a hurtful way. I think it's very important to look at both sides. You see so many of the lovely bubhub ladies hurt badly by their MILs because they treat them as if they've stolen their son's. Luckily, my MIL see's it more like gaining a daughter. I'm one of the lucky ones.